1. Field of the Invention
The present invention relates to a golf ball. More specifically, the present invention relates to a golf ball having a metallic ink printing thereon.
2. Description of the Related Art
Large particle size metallic inks have processing issues, and the luster and sheen of the inks is unappealing.
Heretofore, for the purpose of obtaining written marks with metallic luster such as gold and silver, aqueous ink using glittering pigments have been proposed. For example, Japanese Unexamined Patent Publication Hei 7-118592 proposes an aqueous ink using an aluminum powder pigment. Japanese Unexamined Patent Publication Hei 8-151547 proposes an ink using a pearlescent pigment. Japanese Unexamined Patent Publication Hei 11-29734 proposes an aqueous metallic ink prepared by coloring an aluminum powder with an organic pigment fixed.
Aluminum pigments are used widely in coatings as special-effect pigments. The term special-effect pigments is used to denote pigments which have a directed reflection at oriented, metallic or highly light-refractive particles of a predominantly flat configuration (German Standard DIN 5594). They are always of a plate-like or flake-like configuration and have very large particle diameters compared with dye pigments. Their optical properties are determined by reflection and interference. Depending on transparency, absorption, thickness, single-layer or multi-layer structure, the special-effect pigments exhibit a metallic shine, a pearl shine, interference or interference reflection. The main area of use is in cosmetics and the automobile sector, and in addition in coloring plastic materials, paints, leather coatings, the printing industry and the ceramic industry. (For a comprehensive representation of the technical background, see W. Ostertag, Nachr. Chem. Tech. Lab. 1994, 9, 849).
The aluminum pigments which are most frequently used are aluminum flakes or pigments based on flake-like Cu/Zn-alloys and coated mica flakes, wherein aluminum pigments exhibit a typical metal shine whereas coated mica flakes exhibit a typical pearl shine.
In recent years the need for colored special-effect pigments has increased greatly. Therefore for example oxide-covered copper and brass flakes, substrates which are coated with transition metal oxides such as muscovite, phlogopite or glass, guanine single-crystals (fish silver), BiOCl-single crystals, flake-form haematite single-crystals, flake-form phthalocyanines, micronized titanium dioxide, polished aluminum shot, iron oxide or crushed thin multi-layer films with a Fabry-Perot-structure were used as special-effect pigments.
In comparison, by coloring aluminum pigments, it is possible to produce colored pigments with improved covering capability, compared with pearl shine pigments, and good coloristic options. In that respect, the coloring action is produced either by fixing color pigments by means of polymers, by coating with oxides of different metals using a very wide range of different processes, by coating with a color pigment-bearing oxide layer or by oxidation.
In accordance with U.S. Pat. No. 4,328,042 and EP-A-0 033 457 aluminum flakes are colored by the deposition of iron oxide from iron pentacarbonyl, using a technically very expensive fluidized bed process. That procedure gives rise to gold-colored aluminum pigments.
In accordance with U.S. Pat. No. 5,037,475 color pigments are fixed on the metal surface by carboxyl group-bearing polymers. The pigments obtained however have only a low level of color intensity.
Aluminum pigments are colored in accordance with WO 91/04293 (PCT/US90/05236) by the fixing of polymer-coated color pigments on the metal surface by means of electrostatic forces.
In accordance with EP-A-0 238 906 metal pigments are covered with a titanium dioxide layer by the controlled hydrolysis of an organic titanate ester compound. Various color shades can be achieved by varying the thickness of the oxide layer. For that purpose it is necessary to observe accurately controlled reaction conditions such as pH-value and the rate of adding material by dropping. In order to achieve color effects, it is also necessary to perform a calcination operation which however can only be carried out with difficulty, because of the low melting point of aluminum.
U.S. Pat. No. 4,978,394 describes the production of titanium dioxide-coated aluminum pigments by chemical vapor deposition (CVD) which is technically highly expensive.
U.S. Pat. No. 4,158,074 discloses the production of colored aluminum pigments by coating with a film of hydrated metal oxide. The film is produced by the treatment of fine aluminum flakes or plate portions in an alkaline solution of an iron, nickel, cobalt, zinc or copper salt at elevated temperature by electrochemical reaction of the metal salts.
U.S. Pat. No. 5,261,955 discloses a sol-gel process for the production of colored metal pigments, wherein the metal flakes are dispersed in a sol of an inorganic salt, dispersed after filtration in a solution of an inorganic compound, for example cobalt nitrate, in an organic solvent and finally a sol-gel layer is formed on the flakes by heating.
In accordance with DE 1 95 01 307.7 (Eckart-Werke) aluminum pigments can be colored in a very wide range of different color shades such as for example blue, red, violet and gold, in accordance with a process which is simple from the point of view of the apparatus used, by the controlled hydrolysis of metal acid esters in the presence of color pigments in an organic solvent.
JP-A-61-130375 discloses a gold-colored aluminum pigment, produced by the treatment of aluminum powder with dichromate, sodium fluoride and surface-active agents in acid solution, drying and treatment with a fatty acid derivative. Color shades other than gold cannot be achieved with that process. In addition the toxicity of the chemicals used and their high price represent a major disadvantage of the process.
U.S. Pat. No. 3,067,052 describes colored aluminum pigments which are produced by the oxidation of aluminum powder with KMnO4-solution, possibly with the addition of a reducing agent. The color shade of these pigments is golden, possibly also with a greenish or reddish shade, depending on the respective reducing agent used. In this case also the toxicity of the oxidizing agent has a detrimental effect.